Chair back



FIG. 1 is a rear elevational view of a chair back showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is an elevational view of one side of the chair back, the other side being a mirror image thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a chair back, as shown and described. 